Originally Posted by BuzzinBumble
Starching seems like a huge help and has many enthusiastic practitioners on the topic. I'll have to try it on my next quilt!
If you have not starched before creating your sandwich, you can still spray starch afterwards. Lay the sandwich on a large sheet and spray starch from the edges towards the center (to minimize overspray). Let dry (a fan speeds up this process), then spray again. A few layers of spray starch like this on both sides of the sandwich can help a lot to prevent puckers.